Synthesis, structure and reactivity of NO+, NO˙ and NO− pincer PCN-Rh complexes. Issue 21 (14th May 2020)

• Record Type: Journal Article
• Authors: Gallego, Cecilia Mariel; Gaviglio, Carina; Ben-David, Yehoshoa; Milstein, David; Doctorovich, Fabio; Pellegrino, Juan
• Is Part Of: Dalton transactions. Volume 49:Issue 21(2020)
• Page Start: 7093
• Page End: 7108
• Publication Date: 2020-05-14
• Subjects: Chemistry, Inorganic -- Periodicals; Chemistry, Physical and theoretical -- Periodicals; Chemistry, Inorganic -- Periodicals; 546.05
• DOI: 10.1039/d0dt00962h
• Languages: English
• ISSNs: 1477-9226

Abstract

Abstract : Synthesis of a rhodium PCN pincer-type nitrosyl complex is described. Coordination to the metallic center by weakly coordinating anions was found, as well as a slight stabilization of higher oxidation states when compared to a PCP analogue. Abstract : Synthesis of a pincer-type linear nitrosyl complex [Rh(P t Bu2 CN Et2 )(NO)] + (3 + ) is described. The product and all intermediates involved were fully characterized by FTIR, NMR, cyclic voltammetry and X-ray crystallography. Attempts at obtaining (3 + ) from its chlorinated precursor Rh(PCN)(NO)Cl (2 ) revealed that a relative stabilization of this complex ion is introduced by the BArF − counteranion, as other counteranions—PF6 −, BF4 − and triflate—proved to coordinate to the metal center. Redox reactivity both of (3 + ) and of that of its five-coordinate derivatives (2 ) and [Rh(PCN)(NO)(CH3 CN)] + (4 + ) was found to distinguish itself from analogous PCP complexes due to a relative stabilization of higher oxidation states. Oxidation of these three complexes was studied by FTIR spectroelectrochemistry. Reduction of complex (3 + ) to yield a short-lived {RhNO} 9 species [Rh(PCN)(NO)]˙ (3˙ ) was also carried out. Complex (3˙ ) was proved able to activate carbon–halogen bonds in aryl halides, in much a similar way as that of its PCP analogue. Complex (3 + ) was also seen to establish a linear ↔ bent nitrosyl equilibrium upon addition of CO which could not be fully displaced with excess CO.